Automatic telephone system.



H. E. l-ERSl'HY` AUTOMATIC TLPHONE SYSTEM.

APPLICATION HLED Nov. 28. 1913. RENEWED NNE I, 191s.

Eatcued Jam. QS, 1919.

5 SHEETS-SHEET l.

H. E. HlRSi-EE.` AUTOMATIC TELEPHONE SYSTEM.

APPucATmN man mv. 28.1913. nENE'wED luNE I. :91s.

atented 52m. 28, 19M.

-5 SHEETS-SHEET 2.

H. E. HERSHEY.

MATIC TELEPHONE SYSTEM.

AUT

f \\\APFL!CAT1ON HLED NOV. 28,1913. KENEWED JUNE 7.1918. 1.2952394165.

Patented Jan. 28, MM,

5 SHEETS-SHEET 3.

mgl/MU,

TTOfEm/EYS.

H. E. HERSHEY.

AUTOMATIC TLPHONE SYSTEM.

APPLICATION man Nov. 28. .913. RENEWED JUNE 7. 1918.

lateed Jan.

, HJM).

5 SHEETS-SHEET 5.

HARRY E. HERSHEY, OF WHITE ll'JATElt, KILL ESAS, ASSGNQR T0 AUTTJLATIC ELECTRIC COMIANY,0F CHCAG, lffil'ls, C'RPORATN QF ILLENIS.

Application led November 28, 1913, serial No. 30335552,

To all whom it may concern Be it known that l, HARRY E; Haustier, a citizen 0f the United States of America, and resident of White Water, Butler county,

5 Kansas, have invented certain new and useful Improvements in Automatic Telephone Systems, ofwhich the following is a specifin cation.

My invention relates to automatic telephone systems, and more particularly to the mechanism employed 'for completing a oonnection to a called line. Heretoiore, in the well-known type of automatic system, this connectionV has been completed by means of a l5 connector switch. These connectors are usually divided into groups and each connector isnoinplete in itself.

The object of my invention is 'to simplify the construction oi' these connectors by having each group of connectors provided with one or more .common mechanisms, which. `common mechanism includes certain 'of the elements heretofore individual 'to each connector. For instance, this common mecha- 26 nism can include the usual side switch7 line relay, private magnet, ringer relay and busy relay, and Whenever a connection is efr;

`tended to a connector, this connector' inonojo- 4 olizes one of these common devices and oper- 80 ates to extend the connection to the called line in the usual manner. As soon as the called subscriber answers, however, the con- 1 nector releases this common mechanism and it is then in condition to be used by another 85 connector of the group. ln this manner it is possible to greatly simplify the construction of the connector switches, themselves, and the amount of apparatus constitutirng- `any grou) 0`f connector switches is greatly re- 40 duce These and other objects of my invention -Will be more clearly understood by reference to the accompanying drawings, in which l have illustrated the same in connection with anlautomatic System and switches of a wellknown type.

In the drawings Figures l, 2 and 3 shot' a complete connection between a. calling sub station A (Fig. 1) and a called substr.

on A (Fig. in a system embodying the prin# ciples` of my invention. Fig. fl shows a group of connectors'F, F', etc., with the iliary connectorsI-I,` H', El?, which are to be used by connectors Fgetc. Above'this group,

of connectors'are shown the banks fr? the ieeiitcaticrof Letters atent.

'switches l.

atented dan. 28,

Renewed fune if, l. .serial No. $235,774.

A, selectors E, E', etc., only one level in each selector being shown. The first contact in the level of selector E leads to the connector F, which uses the auxiliary connector H. Thev 'irst'contact in level of selector E leads to the connector F2, which uses the auxiliaryy connector H. ln a similar manner the .first contact in level of selector E2 leads fo connector F4, which will use the auxiliary connector H2. it has been found in practice that three auxiliary connectors allotted 'to ten connectors are suiiicien. Auxiliary connector H is accessible to connectors F', F", etc.,- vv'hile the auxiliary connector is accessible to connectors FZLN, etc, rThis an rangement of auxiliary connectors taken in combination with the slip between selector banks above described nrovides for a mininunnaniount or rotation by a 'selector in huntingtor an is le connector and the auxil-1 iary connector associated therewith. Fig. 5 shows the mechanical struc* re of the auxiliary connector l'l-slioivn in ig. '2.

it fi there is represented an automatic substation to the line conductors of which there is allotted at the central ciiice an in dividual orrline s -Lch C. At I) there is shown master switch for controllinfr a group of the switchesA C. The line switcbhes of this group have 'common access to a numorf trunlr lines which lead to first vselector ri number of first selectors have common access to a number ot' connector switches l? and li", by means of which connection may be completed with subscribers lines` rt Pl is shown auxiliary connector 'which inacontrol, the operations of any number of connectors, such as the connectors F ll, although only two are shown. Associated with thc'auxiliary connector H there shoivn aai-inging current generator R. it a b" is shown having` one terminal grounded and. at Q a busy .machine repre sented.

li'lie Cubstation A shown herein may be of any able or approved t'ype'and comprises theusual receiver 2, transmitter 3, ringer i and condenser Being an automatic-sub station it is also provided with an impulse transmitter or calling device, which is represented herein iy a pair of impulse springs 6 and 7 and an impulse Wheel El, which latter is assumed to be controlled through the medium of ringer hole dial (not shown) in such a manner that the impulse lsprings f5 llo innesca A', it being assumed that the number of 'the substation A is 222. -It will also be explained how, if the called substation is busy, all of the apparatus is automatically released and returned to normal position, whereby the trunks and switches are kept from being made busy, while the'calling subscriber is given a busy signal through the medium of his individual line switch C. Upon the removal of the receiver from the switch-hook at the substation A preparatory tofmaking a call, an energizing circuit is closed through the line relay 13 of the lli/,ne

switch C. This circuit extends from ground V G through the springs 38 and 39, conductor 40, through-the substation A, conductor 41,

through the springs 42 and 43 and through the line .relay 13 to battery B, The line relay 13, upon energizing, operates to close the circuit of the pull-in winding 11. This circuit 'extends from ground G2 through the sp-rin s 44 and 45, through the springs 46 and 4 through the pull-in winding 11 and Ythe springs 48' and 49 to battery B MThe pull-in winding 11 operates to cause the armature 15 to force the springs v38 and 43 out of en'avement with the servings 39 and 42 b b l ,l a

respectively, and also operates to force the plunger on the `plunger arm 9 into the bank of contacts"16V to 23, inclusive. The disengagement oithe springs 33 and 43 from the springs 33 and42 opens the circuit of the line relay 13. The line relay 13 being slow acting does not fall back immediately, however, butI causes the plunger arm 9 to be held in an bperated position until holdingground is supplied to the holding winding 12 from the selector E. The engagement of the springs 16 and 19 with thel springs 20 and' 23, respectively, extends the subscrlbers line to the line relay 35 of the selector E. This circuit is from ground G3 through the vlower windingio the re-ay 35, through the springs 24 and 25, through the springs 23 and .19, conductor 40 to and through the 'substation A, conductor 41, through 'the springs 16 and 2O,y through the springs 26 and 27 and the upper Winding of the relay 35 to battery BL' Therelay 35, upon energizing, closes the circuit of the relay 28 from ground'Gr'* through the springs 29 and 30 and through the relay 23 to battery B. The

relay 28, upon energizing, closes a circuit' for the holding Winding 12 and the relay 14 of the line switch C, said Circuit being from ground G5 through the springs 31 and through the springs 2i and l?, at which point the circuit divides, one part continuing through the holding winding 12 'to battery B. The other part oisaid circuit continues from the spring 17 through the springs 32 and 33 (which are closed at this time by the plunger arm 9)v and through the relay 14 'to battery B. The relay 14, upon energizing, extends a guarding potential to side switch passes to third position.

From ground G8 through the springs 34-and 36 to the private bank contact 37. The relay 28, upon energizing, also prepares the circuit of the vertical magnet 54 and opens the circuit of the release magnet 146 at the springs 147 and 5l. i

The calling subscriber now operates his calling device for the-first digit 2, which momentarily separates the impulse springs 6 and 7 twice. Each time these springs are separated, the first selector line relay 35 deenergizes. Since the relay 28 is a relay which is slow to denergize, its armature does not have time to fallback during the momentary interruptions of its circuit by the line relay 35 Therefore, each time the relay 35 denergizes, a circuit is closed through the vertical magnet from ground G* through the springs 29 and 50, through the springs 51 and 52, relay 53, vertical magnet 54 and the side switch wiper (in first position) to battery B. The two impulses received by the 'vertical magnet 54 cause it: to raise the l supers 56, 57 and 5S two steps to a posi ion opposite vthe second row or level of bank contacts. The slow acting relay 53, which is included in the operating circuit of the vertical magnet, closes a cir cuit through the private magnet. 59 at the first vertical impulse and keeps 'it closed yuntil after the last impulse for the-digit is transmitted, Said circuit extends from ground G7 through. the springs 60 andthe private magnet 59 to battery B'. The relay 53, upon denergizing, breaks the circuit ot the private magnet, which in turn 'denergizes and permits the side switch to pass to second position. n second position the side switch Wiper 55 completes a circuit through the rotary magnet 61. The side switch remains in second position -and causes the rotary magnet to operate in a manner similarlzp that of a buzzer to rotate the wipers step by step over the bank contacts of the second level until the wipers reach the contacts of an idle trunk line, whereupon the The movement of the side switch wiper 55 from second to third position, besides breaking the circuit of the rotary magnet, closes the circuit of the line-switching relay 63. This circuit extends from ground G5 through the springs 31, relay 63 and through 'the side switch wiper 55 (in third position) to battery B. The relay'63, upon energizing, disconnects the line relay 35 from the line and extends the line connection through the line wipers 56 and 58 to the connector F, wheree upon the line relay 64 of the auiliary .connectorH becomes energized over the ollowing circuit: from ground G8 through the lower lwinding of the relay 64, conductor 109, springs 66 and 37 of the relay 68 the ico 'los

nol

isa

53 upon the bank C0 niplas off Hw 'mmh b my; and it w wound pa 1 U im primi@ bmx c Cim.

threj L ik@ vertical 1 x' @prin Q, aina .the 112.10%@ ma@ und S9.

Th@ calling smsA T15 @Ming devia@ for will;

all u asx-ch m 01, the auxiliary Since @ne Eday (35i o- M; is sow acting ji'- 50s,@ m unergz during mala" s circuit f the May muh tima ;J Teli QJ compote from splin -z'md lay 113. This circuit extends from ground G12 throughythe ringing interruptor 114, re lay 113 and the side switch wiper 112 (in third position) to battery B. Since this circuit includes the interruptor 114, the relay 36 f Athe generator R. /Vhen' the called sub- 113 is energized only intermittently. Each time the relayv113 is energized it operates to .disconnect the calling line from the called line and to bridge the generator R across the called line. A. circuit may be traced from one side of the generator lilthrough the springs 116 and 117, conductor 103, springs 125 and 124,'-line wiper 123, bank contact 122, vconductor 41', condenser 5", ringer 4', conductor 40T, barili; contact 121, line wiper 120,'springs 119 and 118, conductor 162 and the springs 126 and 127 to the other side ot' scriber removes his receiver, or as soon thereafter as the relay 113 doe'nergizes, if it happens to 'be'energized at the time, the called substation is provided with talking current over a circuit extending from ground G13 through the right-hand winding oit the relay 115, springs 128 and 129, conductor 101,- springs 130, Springs 131 and 126, conductor 102, springs 118 and 119, line wiper 120, bank contact 121, conductor 4G to and throughthe substation A', conductor 41, bank contact 122, line Wiper 123, springs 124 and 125, conductor 103, springs 117 and 132, springs 133, conductor 100, springs 135 and 134 and the left-hand winding of the relay 115 to batteryv B. All the springs upon the rela-y 115 are adjusted to close their make contacts before any break contacts are opened for this reason: When the relay 115 is energized over the above circuit its armature, upon assuming an operated position, completes a circuit from ground G13 through the right-hand Winding of the relay, 115,l springs '128 and 136, line wiper 120, bank Contact 1211", conductor 40' to and through the substation conductor 41", bank con tact 122, wiper 123, springs 137 and and theleft-hand winding of the relay 115 to battery B. As a result, the relay l115 continues to be energized. '1`.heclosi ug` together oi the springs 138 upon the energization of the relay 115 completes a circuit troni ground G11 through the springs 138, springs 139 and. the left-hand. winding` of the relay 68 to battery B. The springs 139 are adjusted to remain in contact until the armature ot' the relay 68 is entirely pulled down. A circuit is then formed from ground G15 through the right-hand winding of the relay 68, springs 163 and 73, bank contact 72, line wiper 56, springs 71 and 26, springs 20 and 16, conductor 41 to and through the substation A, conductor 40, springs 19 and 23, springs 25 and 70, line wiper 58, bank contact 69, springs 67 and 140 and the left-hand Winding et the relay 68 to battery B., For this reason the relay 68 entirely energizes, and it will be seen that the ow of current through the substation A has been reversed. also, the energization of the relay 68 places ground upon the private wiper 98 from ground G16 through the springs 111 and 141 before the ground from ground G11 is cut oli at the spring 110. Also, the spring 81 is adjusted to malte contact with the spring 142 before it breaks contact with the spring 80. The engagement of the spring 142 with the spring 81 places the ground G16 upon the release trunk to afford a holding circuit for `the relay 63 of the selector E and the relay 14 and winding 12 of the line switch C in place of ground G10. The engagement of the spring 142 with the spring 81' also shunts out the relay 79, whose circuit is opened when the spring 81 disengages from the spring 80. The relay 79, upon dencrgizing, opens the circuit of the vertical and Arotary magnets at thesprings 86, and also closes the release circuit at the springs 88, but the release does not take place at this time, for the circuit is now open at the springs 143. The energization of the relay 68 also opens the circuit of the line relay 64 ofthe auxiliary connector H. The line relay, upon denergizing, opens the circuit of the relay 65. The relay 65 in turn, upon deenergizing, energizes the release magnet 91 over .a circuit extending from ground G1 through the springs 75 and 93, springs 89 and 92, release magnet 91 and the off-normal springs 144 to battery B. The release mag net, upon energizing, restores the side switch to normal position, its own circuit being opened at the oit-normal springs 144 Awhen the side switch reaches rst position. The denergization of the relay 65 also removes the ground G1 from the private bank contaets of all the idle connectors associated 'with the auxiliary connector H, whereupon it in position to receive another call from any of? said connectors.

Upon the completion ot the conversation, the restoring oi the receiver at the substation opens the circuit of the relay 68 of the connector F. The denergization of the relay 68 closes a circuit through the release magnet S7 as follows: from ground G17 through the springs 88, springs 143, release magnet $57' and the olif-normal springs 145 to battery Lacasse connector busy in the selector banks, but also and at the same time it operates to make the fourth and other similar connectors which have access to the first ytumiliary device busy at the selector banks. It will beY seen that normally all of the connectors that have access to an auxiliary device are connected to it, which auxiliary device when brought into operation, sends impulses back which would operate all of the connectors which are associated with a device, were there a selector switch connected with each one of these connectors.

lt will thus be seen that I have devised a very'eiicient arrangement-,by which the present complicate-d connectors can be greatly simplified and in which it is merely necessary to supplement a group of these simpliied connectors with a lless number of auxiliary devices. As these auxiliary devices are only in use during the operation 'of the connector and until the called subscriber answers, but are not tied up during the conversation. it will be readily seenl that the number can be much less than the num ber of connectors in any group. In practice it is found that about three of these auxiliary devices are suiicient to `take care of a group of ten connectors.

lW'hile l have illustrated and described one particular embodiment of my invention, and have shown the same in conncction with Well-known forms of automatic switches', it will, of course, be understood that various changes and modifications can be made without in any way departing from the spirit of my invention.

llVhat claim as my invention is e# 1. ln a telephone system, a plurality of subscribers lines, a group of connectors adapted to establish connection with said lines, and a mechanism common to a plurality of said connectors, said common mechanism being adaptedto operate the shaft and wipers for establishing' connection with a line, and being then adapted to be disconnected from said connector as soon as the called subscriber answers.

2. In a telephone system, a plurality of subscribers lines. a. group of connectors adapted to establish connection lwith said lines, a mechanism common to a plurality of said connectors, said common mechanism beingr adapted to operate the shaft and wipers for establishingl connection With a line, and being then adapted t0 be] disconnected from said connector as soon as the called subscriber answers, and means by whichsaid common mechanism vcan make busy all other connectors which have access to the same.

3. ln a telephone system, a group of connector switche "without line relays and ringer relays, And a mechanism common to said connectors including line relays and ringer relays, said common mechanism adapted to be monopolized by one of said connectors during` operation thereof.

4l. ln a telephone system, a group of connector switches, each connector being without line relays and ringer relays, and common mechanisms less 'in numberthan the connectors, without the provision of shaft and wipers for operating the connector shaft and wipers, said common mechanisms including a line relay and ringer relay, and each commen mechanism being adapted to be made individual to a connector during operation thereo.

5. ln a telephone system, a plurality of lines, a step by step trunking switch for each line, a relay connected to receive impulses from any one of said lines for operating the switch associated therewith.

6. ln a telephone system, a plurality of lines, a trunking switch for each line, a relay connected to receive impulses from any one of said lines for operating the switch associated therewith for extending a circuit to another line, a. signal for said other line. and a source of signaling current individual to said relay and controlled therethrough to signal said other line. l

,7. lin a telephone system, a plurality of lines, a`tru'nlring switch for each line, another line, a relay associated with said first lines to receive impulses from any one of said first lines for operating the switch associated therewith to extend a connection to said other line, a signal forsaid other line, and source-ot signaling current associated with said relay and controlled by said relay for operating' salid signal.

8. ln a telephone system, a. plurality of lines, a trunking switch for eachline, another line, a relay associated with said lirst lines to receive impulses from any one of said first lines for operating' the switch associated thcreuf'ith to extend a connection to said other line, a signal for said other line, a source of signaling current associated with said relay and controlled 'oy said relay for operating said signal, a release circuit controlled over the said other line, release equipment in said release circuit associated with said relay. said release equipment controlled over said other line to disassociate said relay from one of said tirst lines.

9. ln a telephone system, a plurality of lines,- a trunlring switch -for each line, a relay associated with said lines to receive impulses from anyone el. said lines for operating; the switch associated therewith. a plurality of other trunking switches having' access in common to-said lines, a busy test circuitlor said lines, a source of L1ardi11 bT potential, said relay controlling said source for applying a guarding; potential to said busy test circuit whenever one of said other trunk for said. @they mi l :nimmt associm; :d Hed by sa'd :rela/1,' I a, :release Ccu; mi" line, :mid me* d 'haxfewth mv-v 'NL wling mid cflfuy may from @ne of Enid. mgnfyvng smid tout p0- gg- .smid first limos. mem, a plumty of 75 -nty 01 lines a@ i Swi'to am au lines, am-

@tha lim, n, source m ed with Saki. ii y smid relay for up 'n onfsi @van i1', Muller the said xeeas all Y Y lerwt-h relaas@ f4 A 1 l v Lid relay to di -v n of said. sr; m3

potential hugs, and 'iim''emifd over the A is l I ted.

subscli ma a tum ne* 'for cfm lines .i5 f cm'mccted t@ z'bfscribers s l?.

m1 :mmy c'lrlectec to @mi means fm: vsassivey under 1:1 I;

and erminatinff in Gommoni-emv. an aummatie switch associated wii'h e Y rm'i lim., Hwang for ext-Ending :L culling 1. 1e. m an idle trunk line., and .mea-ns for ihfm bnging the switch assoeiatfef] hmmvith lmdv'sf En@ com ity f im for 20. In a, sgp xe Sysem, phuaity L l -autsmatic svvtcxs im vp-Uff: g1; maga in each switch, a bww any. mummia manna Emp? ed to connect mw poke o 4.' said bzxea); 1.0 zf

l of said magnets in mult-link, and a pumity of individual means, one 'En auch aewich, adapted to connes@ 'sho of SMS; battery in mid xr 21. n n. tl

I MS, a plum y of m @im mg; common Mauss to k id ing magnet fm' :fiar-,h switch. u bf. mon means 'fw aonsaalw' the 0f one pole of wir? lmwn L@ 'n'ggnets n mubm, and L plumb n y vidua. mams, one for erich Switch. im.' con-- -necting other poe 0f said bucmj-J tu said magnets sepamixejyj.

22. In, zlaphm system., u ,pluralityof lins, n plurality of automatic swiiuhus hav'- ing common g-afesr te) said linea :m cperaw ing magnet for anc-n switch; multiple com neet-ions fram am@ turmmxl ,of auch magna@ to a commun confxcor, n www of @per ing current, und u appcncunf smid f said iin@ hm, beQn extended. in fmmucii wi; a. fzled ine.

9,5. In n teephono sxxv'smm, u p'huffity vmmvrsor switches for ompletiug connes Hon between culling and cfa'ed lilies, means fm' extending u mlng' Einf; it@ W iiia une U' id fmches7 a rainy summon 'to switches zm ogmabe @var the, m" @Ning line to f.: xtzfl Sii said. Swches imma mes,

2G. n n teephome syS uic-gi:

connector swt,

im Mtv-reen @Ming- :mf saieefl. n for: eni'wugh. f :1 2LH v to an 16M sand switches? a Camlann vitvhoa and o Gaming' liuc. :ma

w which" Suid ii; 'Mam w:

'the Control' of, ray .y fswi'dz mui! b@ l im 'in commit loans Whoz'eby aff' o milo@ infie is completed. voizo 15,0 Common use and the fonos, j

n, cui mig im@ izo am ido one of Said Switches?,

iioi'nmiiy ooiifieosd to me Calling Lino when .So W'Cenciedi commo relay adapted to 'iviio opoifaion of my Switch 'to which ion has boon ex'ende, and moana 1 v .eL oy amai i,

the individual o'mtroi-v rooy io maintain the said. switoh in fated position. L Xn zeejohone system, a. plumity of 354;; fiumi; limos @ach teiimimting in an automatic switch, v14 busy tesi; cixcuit for each zi ii'ie, o, conunon conductor normziiy ormmcto to said circuits in muitipie, roy-- hay, means @by mici relay is enabled bol Qosmio mig?, svi/lches in succession, meuiis;

cmi'foiod 'bjfflssiid relay 'For .connecting a Som: o? 'busy potonml to said conductor the -opeiazion of sw'itex, and o win @bij afior any Switch op@ @i Temo Yom Said com i ik?, test .circuit ai "'ociutod wit/fi SWtob disooimoi. ima 'noi/oy mid coniieobod to said fiom/so goirm foon@ :ij/stem? Subsc'iii;

ti'mu recoivo im vizi the con- Svtoh asm-- i, ,i r; Switches, :i menus control abi; by oniiiog suvsofibey for simguimifsfi I for me, im idiu tmxuking die auxiizwy switch. .mi a teiepione system, a plurality of omomozio working swiiches, n. iessor piuiaiiiiv 01E auxiliary controlling devices, op e akin magiiets in @mail thinking switch? iaajvs in Saiff auxiliary fie'v'ioes for oontroi-- said rfi signets? and moans oontioiod by mii bor for Simultaneously zw ilo 'timiking switoh and Y device.

iii)

lches divided into oontroling meohamsm sub-di :1' 'fi stem, a pumlity o each group, and means an. ido trunkrg 'oop simu Qontrol ing :in 1f for sezfoo i :mii am idlo tlf-univ ing swic d group fsiimitwiieolfsiy, im@A automatic L ,ma for i'onderiug the renmining Wuming s i-ohes, th@ SwlaQt-od gioup u' ooowiblo 3?, in to@ i of j no pronkt lines fui..

ori over the @mmca13 source f; com .W L

afi@ omini connect the aid 'irme terminals to *filo oomiooinod in or :mid @est tot seid conductor, and relays ier c trellin QS 'l I iler l ne xtien er Wil r sal@ ecnneeten.

'ione Syel'en'n plur auteure-,tie sWit einer-ating mag Said switches, multiple cenneciaiene frein terminal of each magnet te u, een# Aien een (luster, e battery, a, ceu'unen rel( trolling the connection er eeiel otherterniinels of seid meguers te se" terrY seperetely.

In e telephone system, e; automatic. ewltehee, an epereti L eeeli swireli, battery, cermrun adapted te ,rcnnee't ene ei? "l te all of .magnete "n plurality ei' 'lividual Svfi'tcll fule'pteu te conne@ said battery 'i seid niegr ln telephone e5 .lineT e Qlarelily com" ef Wipers fer eeeh switch Y ing any Switch te bring;k ite e gegeinent with Sayid line., e, A conductor" *ierlnelly eminecte in re l iple, e source el? ri; sind zi relay lier cfmnee'ing 'with seid source. V

ill). l'r a.. telephone eyetem fi je ecnneeter Switches le? i tien betwee'r callin@ y fer extending e calling lin` of Said Switches, e relay cem'xu switches and operable ever the i calling line te control the Switch, te einen, said line has been extended te eenneit with a, called line, and lousy rest eircuite una' .l the centrol of seid relay fcrrenfleriug remeinler ,0f seid switches ineeeeessilile other calling lines.

lll In a telephone syetem, eeiineeter switches; fer eempl tien between calling eufl l 1 iler extending cellir Seid ewitellesy e 3 J ewilt 'hee enel eperehle wer sul@ reey :fur rendering the reeeiffi: switches inaccessible te fe-.lling linee7 and e, relay controlled eenneeterl celled line for again. renu the remainder of said switches fic te @flier ealle :L r leplwne system, plurality ef Switches for completing cennecw "rr (telling :rn called lines, means e milling line te en idle ene e l ewireheeT e, relay common te Sftcl and. operable over the extended line, e relay for bringing the switch. nich eind. line has been. extended under the eentrel el Said first relay whereby said el). muy be operated to connect with n. cmletl .li el' ei'lclteet circuits for rendering the remaining Switches busy during the 0peretien ef any one of them.

In e telephone system, a'plurality of cenneeter switches for completing connections between ealling and celled lines, ineens ler e2 ending e callin line te :in idle une elf seid switches, e re ay common t0 said.

enel eperehle ever the extended ine, a relay for bringing the switch. eztfl line has been extended under eentrel ef seicl lrst relay whereby Said l' l1 he operated to connect with ai felled le, test ercuits for rendering the m Switches buey during the operai-l aiiy ,of them, and relay mech* wiflierely after the connection te the line .ie completed first relay is; eil te eem? en and the remaining rendered. accessible to other rune System7 a plurality el! i ree, en. individueleeutreleach. switch, ineens fer eze l line te an idle one of Seid commen controlling relay fer normally ecnnectefl to the ezill- .en eo extended, Said common l te centr/el the operation ef which connection has heen Switching" devices whereby erl, :in

Switch ie operated. the calling line pel te the indivi-.filial controlhn relay in multiple l1. Said relay is enabled .es in succession, ineens reley for ci'innecfing; :it ntiel te Said condueter ci? en); ewitelr, :mel

ies each terminating in an eilte--A lli! relay Controlled switching devices Whoi'eby Signed byy at Chcag@j Cook county, fx" miy Switch yisfopemed the busy linos? this 13%: day of November, 1913. otentia is' removed Ppm said conducfmr n u n 5nd the test circuit associated with the op- HR'Y n" HERSH' 5 stated swit'c'l is disconnected from said c m .,unesses:

ducten* und Cmxeed to said somme im zur A. YANGDRQWSEI, other point. R. MORGN. 

